Centrifugal compressor and pump.



H. KELLER.

CENTRIIUGAL GOMPRESSQR AND PUMP.

- APPLICATION FILED JUNE 21, 1907. 987,994.

Patented Mar.28,1911.

/rv Vemtor: Hu/dr'e/'oh Ke//erg .Witnesses:

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UNITED sTaTns PATENT ornron i HULDREICH KELLER, 0F BERLIN, GERMANY, yASSIGNOR TO iGrltNEll't.A L ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CENTRIFUGAL coivrPREssoR am)A PUMP.

Specification of Letters Patent.' Patented M31'. 2S, 1911.

Application filed .Tune 21, 1907. Serial No. 380,052.

useful Improvements in Centrifugal Com- A pressors and Iumps, of which the following is a specification.

The present invention relates to that type of centrifugal compressor` and pump wherein the impeller is arranged to discharge relatively .small jets or streams of liquid, which liquid enters a surrounding conducting apparatus as small pistons between which the air or other gas undergoing compression is confined.

The prior constructions with which I am familiar are open to the objection that the conducting channels in the stationary mem.- ber are either too wide at'their. points of exit or they have a curved formation. Both of these characteristics are objectionable in that they greatly reduce the efficiency of the apparatus. The constructor in broadening the channels in the stationary member', relying upon the familiar form in centrifugal water pumps, overlooked the fact that he was dealing with a compressible fluid and disregarded the fact that in centrifugal air pumps the volume of iuid medium passing through said channels is greatly reduced. Even the channels which have a constant cross-sectional area from the entrance to the exit resultin a loss of efciency. For eX- ainple, assume a conduit or channel having a uniform cross-section and the air compressed from 97% vacuum to atmospheric pressure,

its volume will be decreased to about onethirtieth. 'If the water pistons were initially separated by a distance of millimeters, this distance will decrease Vas the pistons move away from the point of entrance due to the uniform cross-section of'the channel or conduit until they are separated by an amount equal to 60 divided by 30er 2 millimeters. In fact, the pistons will contactwith each other at some point in the channel. If the walls of the channel are curved each water piston as it passes therethrough will, on account of its great centrifugal force, follow the concave wall of the channel and leave a. space between it and the convex wall,

thus permitting the air which has been compressed to expand again and also to retreat from the exit.

For illustration I have specifically mentioned. the disadvantages of a pump having a conducting member with channels of uniform' cross-section,` but it is to be under.-

v stood that they are even greater with channels which expand toward the point of dis-` Charge l I -Tae purpose of my invention is to avoid the objections above set forth and to providel a centrifugal compressor and pump of improyed construction andone having a high efficiency in operation. the accompanying drawing, which illustrates one of the'embodiments of my invention, Figure 1 is a v-iew partially in section,iof an impeller and thersurr-ounding annular member containing the directing channels; and Fig. Q-is an axial section of the same.

1 indicates the main shaft upon which the impeller is mounted, the latter comprising a hub having a flange 2 extending perpendicular to the axis and buckets or vanes 3 and a cover 4. Between the vanes are channels 5 that rapidly decrease in cross sectional area from the entrance to the point of discharge of the periphery. The vanes are so shaped as to cause this reduction in area. The vanes are lnade as sharp asvpossible at the receiving ends and are made smooth so as to avoid losses of all kinds in se far as it'is possible. The water leavingl the impeller will be in the form of thin streams or jets, the continuity of which is interrupted by the walls or partitions of the surrounding mem-v ber 6 as the impeller rotates. This results in the formation of a series of small vwater pistons which pass through the channels in said' member 6 and in so doing carry air or other gas picked up by t-hem as they cross the gap between the stationary and revolving parts.

In the annular stationary member 6 which vis made in the form of a double ring is a plurality of rectlhnear channels 8. Between the two rings 9 andl() are located V-shaped partitions 11 which are thin at their inner ends and widen rapidly toward the periphery. T-lle channels formed between the partitions gradually decrease in width from the point-fof entrance l2 to the point of dischargel'or exit 13, as shown in Fig. 1, the side v'v'ills of the channels being plane surfaces ythat converge toward 4said exit. In other words, the channels decrease in crosssectional area measured in a plane perpen? dicularto the axis. The channels may also decrease, 1n cross-sectlonal area 1n a plane l seneca parallel to the axis, as shown in Fig. 2. The opposed walls of the partitions are straight and the center line ot the channels is substantially tangential to the impeller. By comparing the two figures of the drawing, the marked decrease in cross-sectional area of the channel can be observed. The linear Width of the channels decreases one half trom the entrance to the exit, and the axial width by such an amount that the cross-sectional area ot' each channel at the exit. is only onetourth that ot the entrance; but the invention is not limited to ,these dimensions or proportions. It for example there is a decrease in the volume of, air in these channels to one-thirtieth of the initial, and 4the Water pistons are initially separated. by (5() millimeters, then they will approach each other by about one-seventh `the total distance or to about 9 millimeters, as contrasted with 2 millimeters, previously referred to. Further, the water 'pistons will be about four times as thick at the exit as they were at the entrance, and by reason of this tact are well adapted to resist unilateral excess pressure. In order to obtain greater compression of the air, the decrease in cross-sectional area of the channels toivard the point of exit is made larger. Owing to the character of the channels and the water pistons, all danger of the pistons breaking through is prevented.

lfn lFig. l the shaded parts 14 represent the bodies or pistons oli vater between which are caught or trapped the air pistons l5. lt will be observed thatl the length ot' the air pistons decreases from the center ot' the annular member outward, due to the tact that. they are coniprcssedto a greater or less extent.

ln some cases it will be found desi able to slightly enlarge the channels at the points ot exit as shown at 16 in order to cause a more gentle passage of the 7ater into the inelosing casing.

lhe iinpeller and the water and air or other gas-discharging member are mounted in a suitable casing having a conduitadmitting water or other liquid to the center of the impeller, and a conduit for conveying air or ether'gas to thc-region between the relatively iotating parts of the apparatus. 'Conduit means `is provided for conveying oil' the gais and liquid issuing from the stationary member.

ln accoii'danec with the provisions ot the patent statutes, l have described the principle of operation of my invention, together with the apparatus which l now consider to represent the best embodiment thereof; but l desire to have it understood that the apparatus shown is only illustrative, and

that the invention can be carried out by other means.

l/Vhat I claim as new and desire to secure by Letters Patent of the United States, is,-

l. In an apparatus of the character described, the combination of an impellcr which discharges liquid in jets or streams, a member which surrounds the impeller, and rectilinear channels in the said member whose cross-sectional areas decrease toward the points of discharge.

2. ln an apparatus of the character described, the combination of an impeller which discharges liquid in jets or streams, a member which surrounds theimpeller, and rectilinear channels' or passages in said member, the center lines of said channels extending substantially tangential to the periphery of the impelle1 and the side Walls of each channel being plane surfaces that converge toward its exit so that the crosssectional area of the channel decreases from its entrance to its exit.

ln an apparatus of the character described, the combination of an impeller which discharges liquid in jets or streams, an annulus which surrounds the impeller, and straight channels formed in the annulus for receiving liquid and gas and discharging them outwardly, each of said channels de- `creasing in Width toward the pointv of dis charge measured in an axial plane and decreasing in thickness toward the point ot discharge measured in a plane perpendicular to the axis.

4. ln an apparatus of the character described, the combination of an impeller which discharges liquid in jets or streams, a member which surrounds the impeller, and rectilinear channels in the said member whose cross-sectional areas decrease toward the points ot' discharge-and are slightly enlarged at their ends to decrease the disturlr ance due to t-he liquid entering the inclosing casing.

5. ln a centrifugal pump tor compressing elastic fluids` the combination oit' an impeller with a surrounding conveying agent having channels therein whose middle axis is substantially straight and through which the compressing hquid is discharged in individual slender jets, each channel being sub-` stantially rectilinear for the greater port-ion of its length and decreasing 1n cross-sec- .tional area toward the exit by an amount causing compression of the elastic fluid.

ln witness whereof, I have hereunto set my hand this 24th day of May, 1907.

HULDRECH KELLER.

1Vtlitnesses:

lomos Reimann, KARL (imminenti.

epica tate AHaient may be attained for five eentsceacla, by addressing the Commissioner ai. Patents, 

